MongoServerError: Expected type string but found null

Hey, all. Sorry if this has been asked/answered before, but I had no luck finding anything on the topic. I’m new to both the community, and MongoDB!

I am developing and API using node.js and MongoDB. Locally, I am able to make successful calls to my API through Postman.

However, when making the same exact calls on my deployed site (Azure hosted), I get the exception:

"MongoServerError: Expected type string but found null.\n   
   at Connection.onMessage (/home/site/wwwroot/node_modules/mongodb/lib/cmap/connection.js:205:26 undefined)\n   
   at MessageStream.<anonymous> (/home/site/wwwroot/node_modules/mongodb/lib/cmap/connection.js:64:60 undefined)\n   
   at MessageStream.emit (node:events:514:28 undefined)\n   
   at processIncomingData .processIncomingData (/home/site/wwwroot/node_modules/mongodb/lib/cmap/message_stream.js:117:16 undefined)\n   
   at MessageStream._write (/home/site/wwwroot/node_modules/mongodb/lib/cmap/message_stream.js:33:9 undefined)\n   
   at writeOrBuffer .writeOrBuffer (node:internal/streams/writable:447:12 undefined)\n   
   at _write ._write (node:internal/streams/writable:389:10 undefined)\n   
   at Writable.write (node:internal/streams/writable:393:10 undefined)\n   
   at TLSSocket.ondata (node:internal/streams/readable:817:22 undefined)\n   
   at TLSSocket.emit (node:events:514:28 undefined)"

The exception is thrown upon calling collection.insertOne(document)

I’m at a loss as to what is causing this issue. The document that I am sending to the insertOne function is well defined and contains valid values. I’ve not got any sort of schema definitions either. I’ve tried just about all I know to try.

Has anyone else experienced this problem?

Are you checking you actually received valid data at your API endpoint before you try to insert it into MongoDB? It looks like you have received an empty API call or something.

Hey, Jack. Thanks for the reply! I was actually just about to get on here and respond that I finally resolved my issue. After 8 hours of pulling my hair out, I realized I was chasing a red herring, and the problem was actually being caused by a missing environment variable :man_facepalming:

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And thus it happens to all of us … Congratulations on solving your problem!

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